Endotoxin is also called an intracellular toxin, which term refers comprehensively to toxic substances existing in the cells of Gram-negative bacteria. The components of endotoxin are lipopolysaccharides (hereinafter called "LPS").
In the prior art, the pyrolysis method, the ultrafiltration method, and the affinity chromatographic method with polymixin B are known methods for removing endotoxin.
However, the pyrolysis method is a method which thermally decomposes LPS through a dry heat treatment at 250.degree. C. or higher to remove LPS from glass vessels, etc. by decomposition. This pyrolysis method cannot be utilized for separating LPS from a substance which is unstable to heat. The ultrafiltration method is effective for separation of LPS from low molecular weight substances, but it is not applicable in principle for separation of endotoxin from high molecular weight substances. The affinity chromatographic method with polymixin B may be expected to be practically applied from the point of utilizing the affinity possessed by polymixin B for LPS, but use is limited because of the toxicity of polymixin B and thus, this method has not .been presently practically applied.
Thus, there has not been found yet a practically effective method as the method for separating effectively and stably LPS from among high molecular weight physiologically active substances.
Accordingly, the present inventors have intensively studied in order to find novel substances exhibiting affinity for LPS. In the present invention, this substance is called as LPS-binding polypeptide (sometimes abbreviated to LBP). Consequently, they successfully extracted and isolated a novel polypeptide from horseshoe crab hemocyte, synthesized this polypeptide by the synthetic method such as solid phase peptide synthesis, and further found that said polypeptide exhibits strong affinity for LPS and has biological activities such as antibacterial activity and blastgenesis inhibition action, etc., thus accomplishing the present invention.